Method of producing a stranded wire assembly by friction welding

ABSTRACT

A method for producing a stranded wire assembly whereby a connector member is metallurgically bonded to the end of a stranded wire cable. The wire cable is inserted into one end of a hollow sleeve member until the end of the cable is flush with the opposite end of the sleeve. The sleeve is then mechanically fastened to the cable and the coplanar surface of cable and sleeve is friction welded to the connector.

[451 Apr. 24, 1973 2 Sheets-Sheet 1 BY v f L a /Vr/ wie) l ATTORNEYS Patented April 24, 1973 Patented April 24, 1973 3,728,781

2 Sheets-Sheet-2 I 6o 9o 64 .l INVENTORS RONALD E. CURT|5 GARY ENGLISH BY JAMES R. HENSE (7:, y 7 f j a l ATTgzNEYs METHOD OF PRODUCING A STRANDED WIRE ASSEMBLY BY FRICTION WELDING BACKGROUND OF THE INVENTION connector. Typical of these methods are bolted l0 together split clamps, tapered wedges and sleeves, split sleeves which are collapsed onto the cable, and various combinations of these methods.

Although presently known and used methods for fastening stranded cable to connectors are not always i satisfactory, results must sometimes be comprised if it is necessary or desirable to use stranded cable. The elaborate and time-consuming methods of joining stranded cable to connectors results in rather expensive assemblies.

In the case of an electrical connection, wherein a current carrying stranded cable is fastened to a connector, a copper cable is mechanically fastened to the connector. In most such cases it is necessary to use a relatively large copper cable rather than less expensive aluminum cable, or smaller copper cable, due to the poor electrical conduction across the mechanical connection between cable and connector.

Although a metallurgical bond between the cable and connector, provided by welding, would be most desirable, it would be extremely difficult, if not impossible to weld the stranded cable to a connector using present welding methods and processes. For this SUMMARY AND OBJECTS OF THE INVENTION The present invention relates to a method of producing a stranded wire cable assembly wherein the stranded cable is permanently bonded to a connector and the cable and connector are a honogeneous structure. The end of the cable is sufficiently restrained to allow friction welding of the cable-to the connector. This produces a true metallurgical bond between cable and connector. Friction welding of the conventional or inertia type may be used. l

It is, therefore, an object of this invention to overcome the above-described problems by providing a method of metallurgically bonding a stranded wire cable to a connector member.

It is also an object to restrain the end ofthe cable so that the cable strands can be friction welded to the connector.

It is a further object to friction weld a connector across a common coplanar surface of the cable and a restraining sleeve.

lt is another object to produce a stranded cable assembly having mechanical and electrical conduction properties superior to presently known assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects of this invention will become apparent from the following description and accompanying drawings wherein:

FIG. 1 is a side elevation view illustrating one ernbodiment of a friction welding machine which may be used to practice the method of the present invention;

FIG. 2 is a side view, partially in section, of a stranded wire assembly produced by one of the Prior Art methods',

FIG. 3 is a side view, partially in section of the individual components used in producing an assembly by the instant invention;

FIG. 4 is a side view, partially in section, of a completed assembly produced by the method of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A friction welding machine constructed in accordance with one exemplary embodiment of the present invention is indicated generally by the reference numeral 11 in FIG. 1. As shown, the machine comprises a frame or housing structure generally denoted at 12 for housing the various elements of the machine. The two parts to be welded, workpieces WP- 1 and WP-2 are mounted within chucks 14 and 16.

The chuck 16 does not rotate and is mounted on a tailstock fixture 18. The fixture 18 is mounted for axial movement on the machine frame 12 under the control 'of a load cylinder 20. A pressure control circuit, not shown, regulates the pressure in the load cylinder, and thus determines the force with which the parts WP-l and WP-2 are engaged.

The chuck 14 is mounted on a spindle 22, and the v chuck and spindle are mounted for rotation within the frame l2. The rotary spindle 22 is adapted to receive flywheels 24 which may be of various size and mass depending upon the particular application of the machine.

An electric motor 26 rotates the spindle through a hydrostatic transmission generally indicated by the reference numeral 28. The hydrostatic transmission includes a hydraulic pump 30, a hydraulic motor 32, and a manifold 34 between the pump and motor.

The drive ratio between the motor and the spindle 22 can be varied by changing the cam angles in either the pump 30 or the motor 32, and the motor and pump can be used to effectively disconnect the motor 26 from the spindle 22 by moving the cam of the pump 30 to a position in which the pump 30 does not displace any hydraulic fluid to the motor 32.

It is to be understood that the flywheel weights 24 are mounted on the spindle 22 so that the welding machine ll can be operated as an inertia welding machine as described in U.S. Pat. No. 3,273,233 and as described in further detail below. A welding operation to join a first workpiece, such as an electrical connector designated as WP-l to a second workpiece such as an electrical cable designated as WP-2, for example, can be performed by operating the machine in the following general manner. The first workpiece WP-l is firmly clamped in the rotatable chuck 14 located on the spindle 22. The second workpiece WP-2 is firmly clamped in the non-rotatable chuck 16 which is located on the tailstock portion 18 of the machine. Upon actuation of pieces are brought into contract under the upsetting pressure applied through the ram 20, heat is generated at the contacting surfaces or interface of the weld pieces. This heating increases until the workpieces reach the welding temperature, at which time the upsetting pressure, applied by the ram at either a constant or varying pressure, causes flashing or upsetting to occur. During this heating and flashing, the rotational velocity of the spindle member 22 has continued to decrease. At the time the rotation of the spindle ceases, upsetting has taken place and the weld is completed. The clamping force of chucks 14 and 16 is then released, ram 20 is then deactivated, and the completed weld assembly can be removed from the machine.

A stranded wire connector assembly produced by one of the presently known methods is illustrated in FIG. 2. This assembly 40 is an electrical cable connector assembly and comprises a connector member 42 and a length of cable 44. The connector member 42 contains a solid threaded portion 46 on theone end and a hollow bored portion 48 on the other end. The threaded portion 46 is for connecting the assembly 40 to a terminal (not shown), and the hollow bored portion 48 is for receiving an end of the cable 44. A protective insulative coating 50 surrounds the cable 44 except for the end portion 52 which is inserted into' the bored portion 48 of connector 42.

Using presently known methods, the connector 42 and cable 44 are joined into the assembly 40 by inserting the bare end portion 52 of the cable into the bore 48 of connector 42, and applying a circumferential pressure to the outside surface of the hollow bored portion 48 which causes the portion 48 to collapse on to the cable 44 and become mechanically attached to the cable.,The walls 54 of bored portion 48 can contain one or more longitudinal slots to facilitate collapsing of the connector on to the cable.

In an electrical connector assembly such as 40, electrical current is conducted from the cable 44 to the connector 42 by means of the external cable strands only. This is duel to the nature of the mechanical joint between the connector 42 and the cable 44 wherein only the external strands of cable 44 are in intimate contact with the connector 42. Since current is transmitted from the cable 44 to the connector 42 mainly by the external strands of the cable 44, a larger cable is required to transmit a given amount of current from the cable to the connector. In such an electrical connector assembly, the more expensive copper cable must be used, as opposed to the less expensive aluminum cable, in view of the poor electrical conduction across the mechanicaljoint. v

The friction welded stranded wire cable assembly 60 ofthe present invention, as best shown in FIGS. 3 and 4, comprises a connector member 62, a hollow circular sleeve member 64, and a length of stranded wire cable 66. As depicted in FIGS. 3 and 4, assembly 60^is an electrical conductor assembly, similar to assembly 40 of FIG. 2.

Connector 62 is a solid member containing a threaded portion 68 on one end and a shoulder portion 70 on the other end. The sleeve 64 contains a through bore 72, a first end 74 for receiving the stranded wire cable 66, and a second end portion 76 for mating with the shoulder portion of connector 62. Sleeve 64 contains a longitudinal slot 82 cut through the wall of the sleeve and running the entire length of the sleeve. Although the slot 82 is shown as running parallel to the axis of the sleeve, it could also be cut at a-n angle to the longitudinal axis of the sleeve or in a spiral patternaround the sleeve. A protective coating 78 surrounds the stranded cable 66 except for the end portion 80 which is inserted into the bore 72 of sleeve 64.

The individual components are permanently joined into an assembly in the following manner. The end portion 80 of cable 66 is inserted into the bore 72 of sleeve 64 until the end surface 84 of the cable is flush with the end surface 76 of the sleeve 64. A radially inward compressive force is then applied to the circumferential surface 86 of sleeve 64 which causes the sleeve to collapse on to the cable 66 and thereby mechanically lock the sleeve 64 to the cable 66. End surface 84 of cable 66 and end surface 76 of sleeve 64 now form a common coplanar surface.

The locked together sleeve and cable assembly is then clamped or fastened in a non-rotatable chuck or holding fixture on the tailstock portion of a friction welding machine. The connector member 62 is then clamped in a rotatable chuck or holding fixture on the spindle of the same machine. A friction welding operation, as previously described, is then performed and the common coplanar surface of the sleeve and cable is welded to the shoulder portion 70 of the Vconnector member 62.

The finished friction welded assembly 60 then consists of the sleeve and cable unit friction welded to the connector member at interface88. A true metallurgical bond now exists between the cable 66 and the connector 62. The material of the cable 66 and of the connector 62 are then a homogeneous structure and there is absolutely no hinderance of electrical current flow between the two. Due to the metallurgical bond between the cable and the connector, and the fact that the materials are a homogeneous structure, in the embodiment of an electrical connector assembly, the less expensive aluminum cable can be used to replace` the more expensive copper cable, since full electrical current flow is now available between cable and connectot'. v

After the friction weld operation is completed, the flash 90 produced during the weld operation can be machined away to produce a smooth exterior surface. Once the flash 90 has been removed, there is no external evidence that a weld joint exists between the cable, sleeve and connector.

Although the above description indicates .that the sleeve 64 is mechanically clamped on to the cable 66 while the pieces are outside the confines of the friction welding machine, it would be entirely possible, and even desirable, to allow the clamping force of the holding fixture to produce the force necessary to lock the sleeve on to the cable. This eliminates a separate operation for attaching the sleeve to the cable.

Although the present invention has been described herein with particular reference to its use as an electrical connector assembly, it is to be understood that the disclosed method and article is adaptable for use with other types of materials -and applications, such as steel cable attached to an eye or hook connector. Also, it is to be understood that changes and modification may be made in the above-described methods without departing from the spirit and scope of the present invention as described in the appended claims.

We claim: 1. A method of joining a stranded wire cable to a connector comprising the steps of:

providinga hollow circular sleeve member containing a first and second end and forming in the sleeve a slot traversing the axial length of the sleeve, inserting the wire into the first end of the sleeve until the end surface of the wire is flush with the second end ofthe sleeve to form a coplanar surface, restraining radial outward movement ofthe ends of the strands by applying a radially inward .compressive force to the circumferential surface of the sleeve to reduce the circumferential dimension of the sleeve and thereby mechanically fasten the wire within the sleeve, said compressive force being applied to a holding device forming a portion of a friction welding machine, and

relatively rotating and engaging the connector and the reduced end of the sleeve together, applying an axial load while in rotating rubbing Contact to heat the engaged connector, sleeve, and wire to a plastic state to friction weld the coplanar surface of the sleeve and the wire to the connector.

2. A method as set forth in claim 1 wherein said friction welding is of the inertia type in which the energy required for welding is stored in rotating flywheels. 

1. A method of joining a stranded wire cable to a connector comprising the steps of: providing a hollow circular sleeve member containing a first and second end and forming in the sleeve a slot traversing the axial length of the sleeve, inserting the wire into the first end of the sleeve until the end surface of the wire is flush with the second end of the sleeve to form a coplanar surface, restraining radial outward movement of the ends of the strands by applying a radially inward compressive force to the circumferential surface of the sleeve to reduce the circumferential dimension of the sleeve and thereby mechanically fasten the wire within the sleeve, said compressive force being applied to a holding device forming a portion of a friction welding machine, and relatively rotating and engaging the connector and the reduced end of the sleeve together, applying an axial load while in rotating rubbing contact to heat the engaged connector, sleeve, and wire to a plastic state to friction weld the coplanar surface of the sleeve and the wire to the connector.
 2. A method as set forth in claim 1 wherein said friction welding is of the inertia type in which the energy required for welding is stored in rotating flywheels. 